Along with the development of communication techniques, how to reliably transmit a data service and how to locate the failure quickly when there is a failure during transmitting the data have become important problems that need to be resolved urgently. Therefore, the BFD has emerged as the time requires as a fast detection mechanism. The BFD detects the links via a fast Hello mechanism with a negotiated speed rate.
The BFD can be used for detecting the correctness of various transmissions, such as an Ethernet, a Multiple Protocol Label Switching (MPLS) path, a common route encapsulation and an Internet Protocol Security (IPSec) tunnel.
The BFD fundamentally develops from basic transport techniques, therefore the BFD can detect the failure on any layer of the network. The objective of the BFD is to provide a failure detection mechanism with a low cost and a short detecting period on the path between adjacent routers. The adjacent routers are the routers that connect with each other via one or several logic links, but not limited to one hop between the routers. The BFD can perform a failure detection of an interface, a data link and an extended forwarding engine itself.
The BFD, as a method of failure detection in a lightweight link or a node or an interface, has great advantages in the failure detection on a data plane. At present, the BFD defines a status machine for implementing the failure detection and some necessary parameters for setting up and maintaining a BFD session, and expresses the status machine and the parameters with a data load, such that diversified protocols and media can use the status machine and the parameters mentioned above as the data load while adopting the BFD as a failure detection mechanism on the data plane. However, the BFD itself does not define a method about how to start the BFD session in any media and protocols. Thereby, if adopting the BFD to implement the failure detection on a data plane, there is no detailed implementation scheme at present.
At present, a method about how to adopt the BFD as a Label Switching Path (LSP) failure detection in the MPLS network and an encapsulating method for a BFD load in the MPLS are defined. Meanwhile for the BFD session startup, a method of failure detection on the MPLS LSP data plane is adopted. The corresponding intra-domain LSP detected is as shown in FIG. 1. The intra-domain LSP can be a path between Label Switching Router (LSR) A and LSR B in Domain A. The corresponding inter-domain LSP detected is as shown in FIG. 2. The inter-domain LSP can be a path between LSR A and LSR B located in Domain A and Domain B respectively. In addition, an encapsulation is defined, in which the BFD load is taken as a User Datagram Protocol (UDP) load.
However, the foregoing technique scheme with regard to a method for the MPLS LSP adopting the BFD to implement the failure detection does not take into account the method for adopting the BFD to implement the failure detection on the IP forwarding plane.